Some can destroy the planet, others have the ability to render us extinct, and all have the power to destroy civilization.

How likely are they to occur, and what exactly would happen if they did, and could we survive?

"Last Days on Earth" goes beyond science fiction to science fact.

Using state-of-the-art visual effects, it will take viewers on a journey that is both breathtaking and terrifying, from the outer reaches of the universe to the inner world of DNA, with an around-the-globe tour in between.

"Of all the generations of humans that have walked the surface of the Earth -- for 100,000 years, going back when we first left Africa -- the generation now alive is the most important," said Michio Kaku, professor of theoretical physics at City University of New York.